Liquid ejection control device, liquid ejection system, and control method

ABSTRACT

In a liquid ejection control device, an operation unit includes an energy dial for inputting an energy instructing value related to kinetic energy of a pulsed liquid jet ejected from a liquid ejection device, and a repetitive frequency dial for inputting a repetitive frequency instructing value related to the number of times ejection of the pulsed liquid occurs per unit time. In addition, a controller includes a voltage magnitude setting section that sets voltage magnitude of the drive voltage waveform such that the kinetic energy becomes the energy instructing value, based on a rising index value related to rising of the drive voltage waveform and the repetitive frequency instructing value.

PRIORITY INFORMATION

The present invention claims priority to Japanese Patent Application No.2014-261255 filed Dec. 24, 2014, which is incorporated herein byreference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a liquid ejection control device thatcontrols a liquid ejection device which uses a piezoelectric element andejects a liquid having a pulsed shape.

2. Related Art

A technology, in which a liquid is ejected using a pulsed shape ejectionpulse in order to cut a cutting target object, is known. Ejection of aliquid to have a pulsed shape means a jet flow of liquid is ejected froma nozzle in a pulsating manner, and thus, in this specification, theejection is properly referred to as a “pulsed liquid jet.”

The pulsed liquid jet is variously used, and, for example,JP-A-2005-152127 proposes a technology which is used for performingsurgery in the medical field. In this case, the cutting target object isa living tissue and the liquid is saline.

A mechanism which uses a piezoelectric element is one of the knownmechanisms which is used to generate a pulsed liquid jet. In themechanism, drive voltage having a pulsed wave shape is applied to apiezoelectric element and thereby, the piezoelectric element generatesmomentary pressure such that the liquid is ejected in a pulsed shape.Accordingly, in a case where strength of a pulsed liquid jet is changed,the drive voltage which is applied to the piezoelectric element iscontrolled. Therefore, it is conceivable to use a type of mechanism inwhich a characteristic value of the drive voltage which is applied tothe piezoelectric element, such as a magnitude of a drive voltagewaveform (voltage magnitude, also referred to as a size of drivevoltage) is controlled by an operation unit such as an operation dial,an operation button, or the like, and thereby the strength of the pulsedliquid jet is changeable.

However, even when the characteristic value of the drive voltage whichis controlled by the operation unit is changed, it is often not possibleto change a cutting mode such as a cutting depth or a cutting volume ofthe cutting target object as intended by a user. A detailed descriptionthereof will be provided below, and, for example, in many instances evenwhen a user changes the voltage magnitude to be twice or four times, orhalf or one fourth of the magnitude, the cutting depth or the cuttingvolume is not necessarily changed at equivalent amounts. In a case wherethe pulsed liquid jet is used for surgery, a problem arises in that asurgeon's operation sense does not work as intended.

Meanwhile, if an ejection cycle of the pulsed liquid jet is changeable,it is possible to increase or decrease a cutting depth or a cuttingvolume per unit time and it is possible to adjust a speed of cutting acutting target object. However, since the shape of the drive voltagewaveform is changed when the ejection cycle is changed, the strength ofa liquid jet for one pulse or the like can change. Accordingly, thecutting depth or the cutting volume obtained by a pulsed liquid jet forone pulse changes before and after the ejection cycle is changed, whichcan result in a case where a cutting speed proportional to an ejectionfrequency intended by a user is not obtained even when the ejectioncycle is short, that is, when the ejection frequency is high.

SUMMARY

An advantage of some aspects of the invention is to propose a technologyin which strength of a pulsed liquid jet can be set as intended by auser and usability is improved.

A first aspect of the invention is directed to a liquid ejection controldevice in which a predetermined drive voltage waveform is applied to apiezoelectric element to control the ejection of a pulsed liquid jet ofliquid having a pulsed shape from a liquid ejection device that uses thepiezoelectric element. The liquid ejection control device includes afirst operation unit for inputting a first instructing value related tokinetic energy of the pulsed liquid jet, a second operation unit forinputting a second instructing value related to the number of times ofan ejection of the pulsed liquid is performed per unit time, and avoltage magnitude setting section that sets voltage magnitude of thedrive voltage waveform such that the kinetic energy becomes the firstinstructing value, based on an index value related to rising of thedrive voltage waveform and the second instructing value.

As another aspect of the invention, the invention may be configured as acontrol method in which a predetermined drive voltage waveform isapplied to a piezoelectric element to control the ejection of a pulsedliquid jet of liquid having a pulsed shape from a liquid ejection devicethat uses the piezoelectric element. The control method includesinputting a first instructing value related to kinetic energy of thepulsed liquid jet, inputting a second instructing value related to thenumber of times ejection of the pulsed liquid is performed per unittime, and setting voltage magnitude of the drive voltage waveform suchthat the kinetic energy becomes the first instructing value, based on anindex value related to rising of the drive voltage waveform and thesecond instructing value.

According to the first aspect of the invention, when the firstinstructing value related to the kinetic energy of the pulsed liquid jetand the second instructing value related to the number of times ofejection of the pulsed liquid is performed per unit time are input, thevoltage magnitude of the drive voltage waveform is set such that thekinetic energy becomes the first instructing value based on the indexvalue related to the rising of the drive voltage waveform and the secondinstructing value. As will be described below, a cutting depth or acutting volume is closely related to the kinetic energy of the pulsedliquid jet. Accordingly, direct instruction of the kinetic energy of thepulsed liquid jet enables a cutting depth or a cutting volume, whichmeets a user's intention or operational sense, to be realized andenables usability to be improved.

In addition, it is possible to select the number of times of ejection ofthe pulsed liquid per unit time is performed. In this manner, forexample, it is possible to increase or decrease the number of timesejection is performed per unit of time while the first instructing valueis maintained. Accordingly, it is possible to adjust a cutting speedwithout change in the cutting depth or the cutting volume by the pulsedliquid jet for one pulse before and after the number of times ofejection is changed and improvement of usability is achieved.

A second aspect of the invention is directed to the first aspect of theinvention, in which the liquid ejection control device further includesa third operation unit for inputting a third instructing value relatedto the index value.

According to the second aspect of the invention, it is possible to inputthe third instructing value related to the index value of the drivevoltage waveform.

A third aspect of the invention is directed to the first or secondaspect of the invention, in which the liquid ejection control devicefurther includes a falling shape setting section that changeably sets afalling shape of the drive voltage waveform depending on the secondinstructing value.

According to the third aspect of the invention, the falling shape of thedrive voltage waveform is changeably set, and thereby it is possible tocontrol the repeating ejection of the pulsed liquid jets such that thenumber of times of ejection of the pulsed liquid is performed per unittime becomes the second instructing value while a predetermined ordesirable rising shape of the drive voltage waveform is maintained.

A fourth aspect of the invention is directed to any one of the first tothird aspects of the invention, in which the liquid ejection controldevice further includes a display control unit that performs control ofdisplay of at least one of the first instructing value and the secondinstructing value.

According to the fourth aspect of the invention, it is possible todisplay at least one of the first instructing value related to thekinetic energy of the pulsed liquid jet and the second instructing valuerelated to the number of times of ejection of the pulsed liquid isperformed per unit time. In this manner, it is possible to visuallycheck kinetic energy of the current pulsed liquid jet instructed by auser or the index indicating the number of times of ejection per unittime. Accordingly, it is possible to further improve usability.

A fifth aspect of the invention is directed to any one of the first tofourth aspects of the invention, in which the liquid ejection device iscontrolled such that momentum of the pulsed liquid jet is from 2 nNs(nanonewton seconds) to 2 mNs (millinewton seconds) or kinetic energy isfrom 2 nJ (nanojules) to 200 mJ (millijules).

According to the fifth aspect of the invention, the momentum of thepulsed liquid jet is from 2 nNs to 2 mNs or the kinetic energy is from 2nJ to 200 mJ and it is possible to control the liquid ejection device inthe above range. In this manner, it is suitable for cutting a flexiblematerial such as a living tissue or food, a gel material, or a resinmaterial such as rubber, or plastics.

A sixth aspect of the invention is directed to any one of the first tofifth aspects of the invention, in which the liquid ejection device iscontrolled to cut a living tissue by the pulsed liquid jet.

According to the sixth aspect of the invention, for example, it ispossible to control the strength of the pulsed liquid jet suitable forsurgery.

A seventh aspect of the invention is directed to a liquid ejectionsystem including the liquid ejection control device according to any oneof the first to sixth aspects of the invention, a liquid ejectiondevice, and a feeding pump device.

According to the seventh aspect of the invention, it is possible torealize the liquid ejection system in which the effects of theoperations according to the first to sixth aspects are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view showing an example of an entire configuration of aliquid ejection system;

FIG. 2 is a view showing an internal structure of a liquid ejectiondevice;

FIGS. 3A and 3B are diagrams showing a drive voltage waveform for onecycle of a piezoelectric element and a flow velocity waveform of aliquid at a liquid ejection opening;

FIGS. 4A to 4C are diagrams showing mass flux, momentum flux, and energyflux;

FIGS. 5A to 5C are diagrams showing a flow velocity waveform of aprimary jet which is used in a simulation of a cutting mode of a cuttingtarget object;

FIGS. 6A to 6F are diagrams showing simulation results (cutting depths);

FIGS. 7A to 7F are diagrams showing simulation results (cutting volume);

FIGS. 8A and 8B are diagrams showing simulation results of the flowvelocity waveform of the primary jet in a case where drive voltagewaveforms of different rising frequencies are applied;

FIGS. 9A and 9B are diagrams showing simulation results of the flowvelocity waveform of the primary jet in a case where drive voltagewaveforms of different voltage magnitude are applied;

FIGS. 10A and 10B are diagrams showing simulation results of the flowvelocity waveform of the primary jet in a case where drive voltagewaveforms of different repetitive frequencies are applied;

FIG. 11 is a diagram showing a correspondence relationship among energyE, a rising frequency, and a voltage magnitude, at a predeterminedrepetitive frequency;

FIG. 12 is a diagram showing an operation panel of a liquid ejectioncontrol device according to Example 1;

FIG. 13 is a block diagram showing an example of a functionalconfiguration of the liquid ejection control device according to Example1;

FIG. 14 is a diagram showing an example of a data configuration of anenergy conversion table according to Example 1;

FIG. 15 is a flowchart showing a flow of a process which is performed bya controller during the ejection of a pulsed liquid jet according toExample 1.

FIG. 16 is a diagram showing an operation panel of a liquid ejectioncontrol device according to Example 2;

FIG. 17 is a block diagram showing an example of a functionalconfiguration of the liquid ejection control device according to Example2;

FIG. 18 is a diagram showing an example of a data configuration of anenergy conversion table according to Example 2; and

FIG. 19 is a flowchart showing a flow of a process which is performed bya controller on the occasion of ejection of a pulsed liquid jetaccording to Example 2.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a configuration for realizing a liquid ejection controldevice, a liquid ejection system, and a control method according to theinvention will be described. Further, the invention is not limited tothe embodiments to be described below and a configuration which isapplicable to the invention is not limited to the following embodiments,either. In addition, in description of the drawings, the same signs areassigned to the same components.

Overall Configuration

FIG. 1 is a view showing an example of an entire configuration of aliquid ejection system 1 according to one embodiment of the invention.The liquid ejection system is used for cutting work of a flexiblematerial, for example, for surgery in which a living tissue is a cuttingtarget object, for a food process in which food is the cutting targetobject, for processing of a gel material or for cutting work of a resinmaterial such as rubber or plastics. In the liquid ejection system, apulsed liquid jet having momentum in a range from 2 [nNs (nanonewtonseconds)] to 2 [mNs (millinewton seconds)] or kinetic energy in a rangefrom 2 [nJ (nanojules)] to 200 [mJ (millijules)] is ejected and thecutting target object is cut. Hereinafter, a case where a liquidejection system 1 is used for surgery to perform incision, excision, orlithotripsy (collectively referred to as “cutting”) of an affected area(living tissue) is illustrated. In addition, in description according tothe embodiment, momentum flux and momentum indicate scalar quantity inwhich only an ejecting direction component of a pulsed liquid jet isconsidered, that is, a size.

As shown in FIG. 1, the liquid ejection system 1 includes a container 10which contains a liquid, a feeding pump device 20, a liquid ejectiondevice 30 for ejecting the liquid having a pulsed shape toward a cuttingtarget object, and a liquid ejection control device 70.

In the liquid ejection system 1, the liquid ejection control device 70includes an operation panel 80 on which a surgeon operates duringsurgery. The operation panel 80 is used for inputting various operationssuch as an increase/decrease operation of the kinetic energy. Inaddition, the liquid ejection control device 70 includes an ejectionpedal 83 which is used for switching between ejection start and ejectionstop of the pulsed liquid jet by being pressed with a surgeon's foot.

The container 10 contains a liquid such as water, saline, or liquidmedicine. The feeding pump device 20 supplies the liquid contained inthe container 10 invariably at a predetermined pressure and at apredetermined flow rate through connection tubes 91 and 93 to a pulseflow generator 40 of the liquid ejection device 30.

The liquid ejection device 30 is a section (hand piece) which is grippedand operated by a surgeon during surgery and includes a pulse flowgenerator 40 which applies pulsation to the liquid supplied from thefeeding pump device 20 and generates a pulse flow, and a pipe-likeejection tube 50. The liquid ejection device 30 ejects the pulse flowgenerated by the pulse flow generator 40 as a pulsed liquid jet throughthe ejection tube 50 and, finally, from a liquid ejection opening 61(refer to FIG. 2) provided in a nozzle 60.

Here, the pulse flow means a pulsating flow of a liquid in which theflow velocity or pressure of the liquid significantly and rapidlychanges in terms of time. Similarly, ejection of a liquid having apulsed shape means pulsating ejection of the liquid in which the flowvelocity of the liquid passing through a nozzle significantly changes interms of time. In the embodiment, a case where a pulsed liquid jetgenerated by applying cyclic pulsation to a steady flow is described;however, the invention can be similarly applied to sporadic orintermittent ejection of the pulsed liquid jets in which ejection andnon-ejection of the liquid are repeated.

FIG. 2 is a cross-sectional view illustrating a cross-section of theliquid ejection device 30 in order to illustrate the internalconfiguration of the liquid ejection device 30, the cross-section beingsectioned in an ejection direction. Further, components or portionsshown in FIG. 2 have a vertical and horizontal scale different from thatin reality, for convenience of drawing. As shown in FIG. 2, the pulseflow generator 40 has a configuration in which a piezoelectric element45 and a diaphragm 46 for changing the volume of a pressure chamber 44are disposed in a cylindrical inside space formed by a first case 41, asecond case 42, a third case 43. The cases 41, 42, and 43 are joined onsurfaces facing each other and are integrated.

The diaphragm 46 is a disc-shaped thin metal plate and an outercircumferential portion thereof is interposed and fixed between thefirst case 41 and the second case 42. The piezoelectric element 45 is,for example, a stacked piezoelectric element and one end thereof isfixed to the diaphragm 46 between the diaphragm 46 and the third case 43and the other end thereof is fixed to the third case.

The pressure chamber 44 is a space surrounded by the diaphragm 46 and arecessed section 411 formed in a surface facing the diaphragm 46 of thefirst case 41. An inlet channel 413 and an outlet channel 415 whichcommunicate with the pressure chamber 44 are formed in the first case41. An inner diameter of the outlet channel 415 is formed to be greaterthan an inner diameter of the inlet channel 413. The inlet channel 413is connected to the connection tube 93 and guides the liquid suppliedfrom the feeding pump device 20 to the pressure chamber 44. One end ofthe ejection tube 50 is connected to the outlet channel 415 and theliquid which flows in the pressure chamber 44 is guided to the ejectiontube 50. The nozzle 60, which includes the liquid ejection opening 61having an inner diameter smaller than an inner diameter of the ejectiontube 50, is inserted into the other end (distal end) of the ejectiontube 50.

In the liquid ejection system 1 configured as above, under control bythe liquid ejection control device 70, the liquid contained in thecontainer 10 is supplied at a predetermined pressure or at apredetermined flow rate by the feeding pump device 20 to the pulse flowgenerator 40 through the connection tube 93. Meanwhile, when a drivesignal is applied to the piezoelectric element 45 under the control bythe liquid ejection control device 70, the piezoelectric element 45expands and contracts (arrow A in FIG. 2). Since the drive signalapplied to the piezoelectric element 45 is repetitively applied at apredetermined repetitive frequency (for example, tens of [Hz] tohundreds of [Hz]), the expansion and contraction of the piezoelectricelement 45 are repeated for each cycle. In this manner, pulsation isapplied to the steady flow of the liquid flowing in the pressure chamber44 and the pulsed liquid jets are repetitively ejected from the liquidejection opening 61.

FIG. 3A is a diagram showing an example of a drive voltage waveform L11of a drive signal for one cycle, which is applied to the piezoelectricelement 45 and also showing a flow velocity waveform L13 of the liquidin the liquid ejection opening 61. In addition, FIG. 3B is a diagramshowing a flow velocity waveform (central peak portion) S1 having thehighest peak, which is taken from the peak of the flow velocity waveformL13 in FIG. 3A.

Tp shown in FIG. 3A represents a repetitive cycle (time for one cycle ofthe drive voltage waveform) and a reciprocal of Tp means the repetitivefrequency described above. Further, a repetitive cycle Tp becomes about1 [ms (millisecond)] to 100 [ms] and time (rising time) Tpr required forthe drive voltage waveform to rise to the maximum voltage becomes about10 [μs (microseconds)] to 1000 [μs (microseconds)]. The repetitive cycleTp is set to be a period of time longer than the rising time Tpr. Inaddition, when a reciprocal of the rising time Tpr is the risingfrequency, the repetitive frequency is set as a frequency lower than therising frequency. The rising frequency and the rising time are indexvalues (rising index values) related to rising of the drive voltage.

For example, when the piezoelectric element 45 expands in a case where apositive voltage is applied, the piezoelectric element rapidly extendsduring rising time Tpr and the diaphragm 46 is pushed by thepiezoelectric element 45 and is bent toward the pressure chamber 44side. When the diaphragm 46 is bent to the pressure chamber 44 side, thevolume of the pressure chamber 44 becomes smaller and the liquid in thepressure chamber 44 is pushed out from the pressure chamber 44. Here,since the inner diameter of the outlet channel 415 is greater than theinner diameter of the inlet channel 413, the fluid inertance and fluidresistance of the outlet channel 415 is smaller than the fluidresistance of the inlet channel 413. Accordingly, most of the liquidpushed out from the pressure chamber 44 through rapid expansion of thepiezoelectric element 45 is guided to the ejection tube 50 through theoutlet channel 415, and then a liquid droplet having a pulsed shape,that is, a pulsed liquid jet, is formed by the liquid ejection opening61 having a diameter smaller than the inner diameter of the ejectiontube and is ejected at a high speed.

After the voltage is increased to the maximum voltage, the drive voltageis gradually lowered. Then, the piezoelectric element 45 is contractedover a period of time longer than the rising time Tpr and the diaphragm46 is pulled by the piezoelectric element 45 and is bent to the thirdcase 43 side. When the diaphragm 46 is bent to the third case 43 side,the volume of the pressure chamber 44 is increased and the liquid isguided into the pressure chamber 44 from the inlet channel 413.

Further, since the feeding pump device 20 supplies the liquid at thepredetermined pressure or at the predetermined flow rate to the pulseflow generator 40, the liquid (steady flow) flowing in the pressurechamber 44 is guided to the ejection tube 50 through the outlet channel415 and is ejected from the liquid ejection opening 61 when thepiezoelectric element 45 does not perform expansion and contractionoperations. Since the ejection is performed as a liquid flow at aconstant and low speed, the liquid flow is referred to as the steadyflow.

Principle

A value, by which the pulsed liquid jet is characterized, is based onboth the drive voltage waveform L11 and the flow velocity waveform L13of a jet for one pulse in the liquid ejection opening 61 shown in FIG.3A. The central peak portion (a jet of the peak wave) having the maximumflow velocity, which is generated immediately after rising of the drivevoltage taken from FIG. 3B, is noticeable. Another low peak is formeddue to a jet which is ejected collaterally through back and forthreflection of a wave having pressure fluctuation, which is generated inthe pressure chamber 44 at the time of expansion of the piezoelectricelement 45, within the ejection tube 50; however, what determines acutting mode such as a cutting depth or a drive voltage of the cuttingtarget object is the jet (hereinafter, referred to as a primary jet) ofthe peak wave in which the flow velocity is greatest.

However, in a case where strength of the pulsed liquid jet is changedsuch that the cutting depth or the cutting volume of the cutting targetobject is changed, the drive voltage waveform of the piezoelectricelement 45 is controlled. It is conceivable to employ a method in whichthe control of the drive voltage waveform is performed by a surgeon whoinstructs a rising frequency of the drive voltage waveform or magnitude(voltage magnitude) of the drive voltage waveform as a voltagecharacteristic value thereof. For example, it is conceivable to employ amethod in which a surgeon instructs the rising frequency (or, the risingtime Tpr) at a state at which the voltage magnitude is fixed, or thesurgeon instructs the voltage magnitude in a state in which the risingfrequency is fixed. This is because the voltage magnitude or the risingfrequency (rising time Tpr) thereof has a significant influence on aflow velocity waveform of the primary jet. After the drive voltage isincreased to the maximum voltage, the drive voltage gradually loweredfrom the maximum voltage has little influence on the flow velocitywaveform of the primary jet. Accordingly, when the rising frequencybecomes high or the voltage magnitude is increased, it is consideredthat the cutting depth is increased and the cutting volume is increasedproportional thereto.

However, a cutting depth or a cutting volume of the cutting targetobject is not necessarily changed in proportion to the increase anddecrease of the voltage characteristic value in some cases, and as such,usability deteriorates. For example, a case can be brought about, inwhich the cutting depth or the cutting volume is not increased asexpected even when a surgeon increases the voltage magnitude two timesor the cutting depth or the cutting volume is not decreased as designedeven when the voltage magnitude is decreased to be half. Accordingly,there can be an occurrence of a situation in which a surgeon does notachieve a desirable cutting depth or cutting volume. This is a problemwhich results in extension of surgery time.

In addition, there is a case in which a cutting speed needs to beadjusted, independent of the strength of the pulsed liquid jet. As atype of method for this, it is conceivable to employ a method in which asurgeon instructs the repetitive frequency of the drive voltagewaveform. For example, to increase the repetitive frequency means thatthe number of times of ejection of the pulsed liquid jets per unit timeis increased, and the finally achieved cutting depth or cutting volumeis changed.

However, the drive voltage waveform is changed when the repetitivefrequency is changed. Therefore, even when the repetitive frequency ischanged, the cutting depth or the cutting volume per unit time is notchanged in proportion thereto and a surgeon performs surgery withdeteriorated usability. Specifically, it is conceivable to employ amethod in which the entire drive voltage waveform is simply extended andcontracted in a time axis direction, and thereby the repetitivefrequency is changed. However, in this method, since the risingfrequency which has a significant influence on the flow velocitywaveform of the primary jet is likely to be changed, the strength of thepulsed liquid jet is likely to be changed as described above.Accordingly, a cutting speed is not achieved in proportion to therepetitive frequency, as intended.

Therefore, the flow velocity waveform of the primary jet is focused andcorrelations between several parameters, which are determined dependingon the flow velocity waveform of the primary jet, and the cutting depthand the cutting volume are examined. This is because it is possible tocontrol the piezoelectric element 45 with the optimum drive voltagewaveform for achieving the cutting depth or the cutting volume as exactas a surgeon's operation sense when a parameter having a closecorrelation with the cutting depth or the cutting volume is found.

First, mass flux [kg/s], momentum flux [N], and energy flux [W] of theprimary jet passing through the liquid ejection opening 61 are examined,based on a flow velocity waveform v [m/s] of the primary jet in theliquid ejection opening 61. The mass flux corresponds to amass [kg/s] ofthe liquid passing through the liquid ejection opening 61 per unit time.The momentum flux corresponds to momentum [N] of the liquid passingthrough the liquid ejection opening 61 per unit time. The energy fluxcorresponds to energy [W] of the liquid passing through the liquidejection opening 61 per unit time. Further, the energy indicates thekinetic energy, and, hereinafter, is abbreviated to “energy”.

Since the liquid is released to a free space from the liquid ejectionopening 61, pressure can be set nearly to “0”. In addition, a speed in adirection (radial direction of the liquid ejection opening 61)orthogonal to a jet ejecting direction of the liquid can be set nearlyto “0”. When it is assumed that the liquid has no speed distribution inthe radial direction of the liquid ejection opening 61, it is possibleto obtain mass flux Jm [kg/s], momentum flux Jp [N], and energy flux Je[W] of passing through the liquid ejection opening 61 by the followingequations (1), (2), and (3). S [m²] represents a sectional area of anozzle and ρ [kg/m³] represents working fluid density.

Jm=S·ρ·v  (1)

Jp=S·ρ·v ²  (2)

Je=½·p·S·v ³  (3)

FIGS. 4A to 4C are diagrams showing mass flux Jm (4A), momentum flux Jp(4B), and energy flux Je (4C) which are obtained from the flow velocitywaveform of the primary jet shown in FIG. 3B. When the mass flowvelocity Jm, the momentum flux Jp, and the energy flux Je areintegrated, respectively, within a period of time (duration time) T fromrising to falling of the flow velocity waveform of the primary jet, itis possible to obtain mass, momentum, and energy of the liquid ejectedfrom the liquid ejection opening 61, as the primary jet.

It is conceivable that the cutting depth and the cutting volume by a jetfor one pulse can be determined from the respective values of the massflux Jm, the momentum flux Jp, the energy flux Je, the mass, themomentum, and the energy which are calculated in the manner describedabove. Here, all the values are a physical quantity containing amountcorresponding to the steady flow and, more importantly, are valuesobtained by excluding an amount corresponding to contribution to thesteady flow.

Therefore, in terms of mass flux Jm in FIG. 4A, two parameters of themaximum mass flux Jm_max [kg/s] obtained by subtracting mass flux Jm_BG[kg/s] of the steady flow from the peak value (maximum value) of themass flux Jm, and discharge mass M [kg], which is obtained bysubtracting the amount corresponding to the steady flow from mass of theliquid discharged as the primary jet from the liquid ejection opening 61and is shown by being hatched in FIG. 4A, are defined. The dischargemass M is represented by the following equation (4).

M=∫(Jm−Jm_BG)dt  (4)

In terms of momentum flux Jp in FIG. 4B, two parameters of the maximummomentum flux Jp_max [N] obtained by subtracting momentum flux Jp_BG [N]of the steady flow from the peak value (maximum value) of the momentumflux Jp, and momentum P [Ns], which is obtained by excluding the amountcorresponding to the steady flow from momentum of the liquid dischargedas the primary jet from the liquid ejection opening 61 and is shown bybeing hatched in FIG. 4B, are defined. The momentum P is represented bythe following equation (5).

P=∫(Jp−Jp_BG)dt  (5)

In terms of energy flux Je in FIG. 4C, two parameters of the maximumenergy flux Je_max [W] obtained by subtracting energy flux Je_BG [W] ofthe steady flow from the peak value (maximum value) of the energy fluxJe, and energy E [J], which is obtained by subtracting the amountcorresponding to the steady flow from energy of the liquid discharged asthe primary jet from the liquid ejection opening 61 and is shown bybeing hatched in FIG. 4C, are defined. The energy E is represented bythe following equation (6).

E=∫(Je−Je_BG)dt  (6)

Here, an integration section in the above equations (4), (5), and (6) istime (duration time) T from rising to falling of the primary jet in therespective flow velocity waveforms.

Therefore, it is examined how closely the six parameters of the maximummass flux Jm_max, the discharge mass M, the maximum momentum fluxJp_max, the momentum P, the maximum energy flux Je_max, and the energy Eare correlated with the cutting depth and the cutting volume,respectively, using a numerical simulation.

Here, the pulsed liquid jet is a fluid and the cutting target object isa flexibly elastic body. Accordingly, an appropriate breakdown thresholdvalue is set on the flexibly elastic body side so as to perform asimulation of breakdown behavior of the cutting target object by thepulsed liquid jet, and so-called interaction analysis (fluid/structureinteraction analysis (FSI)) of a fluid and a structure (here, a flexiblyelastic body) has to be performed. Examples of a calculation techniqueof the simulation include a technique using a finite element method(FEM), a technique using a particle method represented by smoothedparticle hydrodynamics (SPH) or the like, a technique of combination ofthe finite element method and the particle method, or the like. There isno particular limitation on a technique applied here, and thus detaileddescription thereof is not provided; however, the optimal technique wasselected taking into account stability of an analysis result,calculation time, or the like, and the simulation was performed.

On the occasion of the simulation, fluid density was set to 1 [g/cm³], adiameter of the liquid ejection opening 61 was set to 0.15 [mm], and astandoff distance (distance from the liquid ejection opening 61 to thesurface of the cutting target object) was set to 0.5 [m]. In addition,it was assumed that the surface of the cutting target object was aflexibly elastic flat body, and, as a physical model thereof, aMooney-Rivlin hyperelastic body having modulus of elasticity of about 9[kPa] (about 3 [kPa] in shear modulus conversion) in Young's modulusconversion, when density was set to 1 [g/cm³], was used. As thebreakdown threshold value, deviation equivalent strain was set to 0.7.

According to the flow velocity waveform of the primary jet, various flowvelocity waveforms of the primary jets are assumed and a total of 27types were prepared in terms of three types of waveforms of a sine wave,a triangle wave, and a rectangular wave which are modified to have threetypes of magnitudes (the maximum value of the flow velocity) in a rangeof 12 [m/s] to 76 [m/s] and to have three types of duration time in arange of 63 [μs] to 200 [μs]. Further, the flow velocity of the steadyflow is set to 1 [m/s].

FIGS. 5A to 5C are diagrams showing a sine wave (5A), a rectangular wave(5B), and a triangular wave (5C) which are applied as the flow velocitywaveform of the primary jet in the simulation. A wave of which theduration time shown in a solid line is 63 [μs], a wave of which theduration time shown in a dashed line is 125 [μs], and a wave of whichthe duration time shown in a two-dot chain line is 200 [μs] wereprepared. Therefore, a pulsed liquid jet to which the prepared waveformis applied as the flow velocity waveform of the primary jet wasgenerated, a simulation of breakdown behavior of the flexibly elasticbody, when the jet is ejected to the flexibly elastic body, wasperformed, and examination of the cutting depth or the cutting volumewas performed.

FIGS. 6A to 6F are diagrams showing simulation results which areplotted, in which the vertical axis represents the cutting depth of thecutting target object and the horizontal axis represents the maximummass flux Jm_max (6A), the discharge mass M (6B), the maximum momentumflux Jp_max (6C), the momentum P (6D), the maximum energy flux Je_max(6E), and the energy E (6F). In FIGS. 6A to 6F, a simulation resultobtained when a sine wave having the duration time of 63 [μs] is appliedas the flow velocity waveform of the primary jet is plotted as a “*”, asimulation result obtained when a sine wave having 125 [μs] is appliedis plotted as a “♦”, a simulation result obtained when a sine wavehaving 200 [μs] is applied is plotted as a “−”. In addition, asimulation result obtained when a triangle wave having the duration timeof 63 [μs] is applied as the flow velocity waveform of the primary jetis plotted as a “+”, a simulation result obtained when a triangle wavehaving 125 [μs] is applied is plotted as a “x”, a simulation resultobtained when a triangle wave having 200 [μs] is applied is plotted as a“▪”. In addition, a simulation result obtained when a rectangular wavehaving the duration time of 63 [μs] is applied as the flow velocitywaveform of the primary jet is plotted as a “•”, a simulation resultobtained when a rectangular wave having 125 [μs] is applied is plottedas a black triangle, a simulation result obtained when a rectangularwave having 200 [μs] is applied is plotted as a “−”.

As shown in FIGS. 6A, 6C, and 6E on the upper stage, it turns out thatrelationships between three respective parameters of the maximum massflux Jm_max, the maximum momentum flux Jp_max, and the maximum energyflux Je_max and the cutting depth are not close because dispersionthereof becomes great due to the shape of the waveform applied as theflow velocity waveform of the primary jet. Particularly, since the massflux is a value proportional to the flow velocity, it is indicated thatthe cutting depth is not determined only by the maximum flow velocity ofthe primary jet.

Next, when relationships between three respective parameters of thedischarge mass M, the momentum P, and the energy E shown in FIGS. 6B,6D, and 6F on the lower stage and the cutting depth are considered, therelationship between the discharge mass M and the cutting depth is notclose because dispersion thereof becomes great by the shape of thewaveform applied as the flow velocity waveform of the primary jet. Incomparison, in terms of the relationship with the momentum P and theenergy E, dispersion is small by the shape of the applied waveform andthe respective plots are distributed substantially on the same curve. Interms of the momentum P and the energy E, the momentum P has lessdispersion. Accordingly, the cutting depth has a close correlation withthe momentum P or the energy E and, particularly, has a strongcorrelation with the momentum P.

Further, the simulation was performed in a case where the diameter ofthe liquid ejection opening was 0.15 [mm] and the standoff distance was0.5 [mm]; however, the simulation was performed with a differentdiameter of the liquid ejection opening or a different standoff distanceand it was confirmed that a qualitative inclination, in which thecutting depth has a close correlation with the momentum P or the energyE, was not significantly changed.

FIGS. 7A to 7F are diagrams showing simulation results which areplotted, in which the vertical axis represents the cutting volume of thecutting target object and the horizontal axis represents the maximummass flux Jm_max (7A), the discharge mass M (7B), the maximum momentumflux Jp_max (7C), the momentum P (7D), the maximum energy flux Je_max(7E), and the energy E (7F). The relationships between the shapesapplied as the flow velocity waveform of the primary jet and the typesof plots are the same as those in FIGS. 6A to 6F.

As shown in FIGS. 7A, 7C, and 7E on the upper stage, it is consideredthat relationships between three respective parameters of the maximummass flux Jm_max, the maximum momentum flux Jp_max, and the maximumenergy flux Je_max and the cutting volume are not close, although therelationships are closer than those with the cutting depth, becausedispersion thereof occurs by shapes of waveforms applied as the flowvelocity waveform of the primary jet.

Next, when relationships between three respective parameters of thedischarge mass M, the momentum P, and the energy E shown in FIGS. 7B,7D, and 7F on the lower stage and the cutting volume are considered, therelationship between the discharge mass M and the cutting volume is notclose because dispersion thereof becomes great by the shapes of thewaveforms applied as the flow velocity waveform of the primary jet,similar to the cutting depth. Meanwhile, in terms of the relationshipwith the momentum P and the energy E, dispersion is small by the shapesof the applied waveforms, similar to the cutting depth, and therespective plots are distributed substantially on the same straightline. In addition, the energy E has less dispersion, compared to themomentum P. Accordingly, the cutting volume has a close correlation withthe momentum P or the energy E and, particularly, has a strongcorrelation with the energy E.

Further, the simulation was performed in a case where the diameter ofthe liquid ejection opening was 0.15 [mm] and the standoff distance was0.5 [mm]; however, the simulation was performed with a differentdiameter of the liquid ejection opening or a different standoff distanceand it was confirmed that a qualitative inclination, in which thecutting volume has a close correlation with the momentum P or the energyE, was not significantly changed.

Based on the above examination results, in the embodiment, the energy Eis focused. Also, a simulation is performed in advance with arepresentative waveform as the drive voltage waveform which is actuallyapplied to the piezoelectric element 45 and a correspondencerelationship among the energy E, the rising frequency, the voltagemagnitude, and the repetitive frequency is obtained.

For this reason, first, a control parameter was changeably set and aflow velocity waveform of the primary jet was obtained through asimulation. The simulation can be easily performed using a numericalsimulation by using an equivalent circuit method based on a model inwhich a channel system of the liquid ejection device is replaced withfluid (channel) resistance, fluid inertance, fluid compliance, or thelike. Otherwise, if higher accuracy is required, a fluid simulationusing a finite element method (FEM), a finite volume method (FVM), orthe like, may be used.

First, the voltage magnitude and the repetitive frequency were fixed, adrive voltage waveform generated by changing the rising frequency in astepwise manner was applied, and a flow velocity waveform of the primaryjet was obtained through a simulation. FIG. 8A is a diagram showing anexample of the applied drive voltage waveform. The respective drivevoltage waveforms are generated when the voltage magnitude is set to V2,a repetitive cycle Tp is set to T2, and the rising time Tpr is extendedfrom T21 to T25 in a stepwise manner (the rising frequency is lowered ina stepwise manner).

FIG. 8B is a diagram showing a simulation result of the flow velocitywaveform of the primary jet in a case where respective drive voltagewaveforms having different rising frequencies shown in FIG. 8A areapplied. As shown in FIG. 8B, when the rising frequency is lowered (therising time Tpr is extended), the flow velocity waveform of the primaryjet has a start timing of rising which is not changed and has extendedduration time to the rising and has the flow velocity magnitude (maximumvalue of the flow velocity) which becomes smaller.

Second, the rising frequency and the repetitive frequency were fixed, adrive voltage waveform generated by changing the voltage magnitude in astepwise manner was applied, and a flow velocity waveform of the primaryjet was obtained through a simulation. FIG. 9A is a diagram showing anexample of the applied drive voltage waveform. The respective drivevoltage waveforms are generated when the rising time Tpr is set to T31,a repetitive cycle Tp is set to T33, and the voltage magnitude isdecreased from V31 to V35 in a stepwise manner.

FIG. 9B is a diagram showing a simulation result of the flow velocitywaveform of the primary jet in a case where drive voltage waveformshaving different voltage magnitudes shown in FIG. 9A are applied. Asshown in FIG. 9B, when the voltage magnitude is decreased, in the flowvelocity waveform of the primary jet, which is different from that inthe case where the rising frequency is lowered, duration time for risingis maintained and the flow velocity magnitude (maximum value of the flowvelocity) becomes smaller.

Third, the rising frequency and the voltage magnitude were fixed, adrive voltage waveform generated by changing the repetitive frequency ina stepwise manner was applied, and a flow velocity waveform of theprimary jet was obtained through a simulation. FIG. 10A is a diagramshowing an example of the applied drive voltage waveform. The respectivedrive voltage waveforms are generated when the rising time Tpr is set toT4, the voltage magnitude is set to V4, and the repetitive cycle Tpextended from T41 to T45 in a stepwise manner (the repetitive frequencyis lowered) in a stepwise manner by widening a rising shape in the timeaxis direction after the drive voltage is increased to the maximumvoltage.

FIG. 10B is a diagram showing a simulation result of the flow velocitywaveform of the primary jet in a case where drive voltage waveformshaving different repetitive frequencies shown in FIG. 10A are applied.As shown in FIG. 10B, when the repetitive frequency is lowered (therepetitive cycle Tp is extended), the flow velocity waveform of theprimary jet has extended duration time which is not as long as that in acase where the rising frequency is lowered. The flow velocity magnitude(maximum value of the flow velocity) is maintained.

Subsequently, energy E was obtained for each flow velocity waveform ofthe obtained primary jet. To be more exact, while the repetitivefrequency was changed in the manner described with reference to FIGS.10A and 10B, both simulation cases where the voltage magnitude was fixedand the rising frequency was changed in the manner described withreference to FIGS. 8A and 8B and a simulation where the rising frequencyis fixed and the voltage magnitude is changed in the manner describedwith reference to FIGS. 9A and 9B, were performed for each repetitivefrequency. Also, energy E of the flow velocity waveform of the primaryjet obtained through each simulation was obtained.

FIG. 11 is a diagram showing a correspondence relationship among energyE, the rising frequency, and the voltage magnitude, obtained at thepredetermined repetitive frequency (for example, described as “F51”).FIG. 11 is made by depicting contour lines related to the energy E on acoordinate space with the vertical axis representing the risingfrequency, and the horizontal axis representing the voltage magnitude.The energies E51, E52, and the like on each contour line become lesstowards the lower left and become greater by a predetermined amounttowards the upper right in FIG. 11. Further, although not shown, if theenergies E obtained at another repetitive frequency are plotted at thesame coordinate space and depicted with contour lines, a contour linediagram is obtained in terms of a correspondence relationship among theenergies E, the rising frequencies, and the voltage magnitudes at therepetitive frequency.

Here, what is focused is that the energies E are not linearly changedwith respect to a parameter in each coordinate axis direction. Forexample, in the correspondence relationship between the energies E, therising frequencies, and the voltage magnitudes shown in FIG. 11, a caseis conceivable, in which the rising frequency is fixed (for example,f5), the voltage magnitude is changeable, and the drive voltage waveformof the piezoelectric element 45 is controlled. In a case where an amountof change of the energies E is constant, a voltage magnitude changebetween the voltage magnitudes V51 and V52 is required between theenergies E51 and E52 and a voltage magnitude change between the voltagemagnitudes V52 and V53 is required between the energies E52 and E53.However, a voltage magnitude interval of the voltage magnitudes V51 andV52 is different from a voltage magnitude interval of the voltagemagnitudes V52 and V53. This phenomenon remarkably occurs as the energyE is increased. Accordingly, when the rising frequency is fixed and anoperation of changing the voltage magnitude by a constant amount isperformed, the energy E is not changed as intended, which results in asituation in which the cutting depth or the cutting volume is notchanged as intended by a surgeon or as exact as a surgeon's sense. Thesame is true for the case where the voltage magnitude is fixed and anoperation of changing the rising frequency by a constant amount isperformed.

Therefore, in an embodiment of the present invention, as an operationperformed by a surgeon during surgery, at least an increase/decreaseoperation of the energy E and an increase/decrease operation of therepetitive frequency energy E are received and a table of thecorrespondence relationships between the energies E, the risingfrequencies, and the voltage magnitudes for the respective repetitivefrequencies on the contour lines obtained for the respective repetitivefrequencies described above is made in advance. Also, in response to theincrease/decrease operation of the energy E and the increase/decreaseoperation of the repetitive frequency by a surgeon, the rising frequencyand the voltage magnitude corresponding to the energy E indicated fromthe correspondence relationship according to the instructed repetitivefrequency are specified and driving of the piezoelectric element 45 iscontrolled.

Example 1

First, Example 1 is described. FIG. 12 is a diagram showing an operationpanel 80-1 which is provided in a liquid ejection control device 70-1according to Example 1. As shown in FIG. 12, on the operation panel80-1, an energy dial 811 as a first operation unit, a repetitivefrequency dial 813 as a second operation unit, a power button 82, anejection button 84, a pump drive button 85, and a liquid crystal monitor87 are disposed.

The energy dial 811 is for inputting an instructing value of energy E(energy instructing value) as a first instructing value, and has aconfiguration in which five-level dial positions, to which, for example,scales of “1” to “5” are assigned, are selectable. A surgeon increasesor decreases the energy E in five levels by switching between the dialpositions of the energy dial 811. For example, an energy instructingvalue is allocated to each position of the dial in advance such that theenergy is increased by a constant amount in proportion to a numericalvalue on a corresponding scale. Further, the number of levels of thedial positions is not limited to five and may be appropriately set suchas three levels of “large”, “intermediate”, and “small”, or possiblyadjustment with no level.

The repetitive frequency dial 813 is for inputting an instructing valueof a repetitive frequency (repetitive frequency instructing value) as asecond instructing value, and, similar to the energy dial 811, has aconfiguration in which five-level dial positions of “1” to “5” areselectable. Further, when it is assumed that a surgeon mainly performsthe increase/decrease operation of the energy E, the repetitivefrequency dial 813 may be configured to include an activate switch forswitching between validity and invalidity of an operation with respectto the repetitive frequency dial 813. The surgeon increases ordecreases, in five levels, the repetitive frequency (for example, fromtens of [Hz] to hundreds of [Hz]) of the drive voltage waveformrepetitively applied to the piezoelectric element 45 by switchingbetween the dial positions of the repetitive frequency dial 813. Forexample, a repetitive frequency instructing value is allocated to eachposition of the dial in advance such that the repetitive frequency isincreased by a constant amount in proportion to a numerical value on acorresponding scale. Further, the number of levels of the dial positionsis not limited to five and the number of levels may be appropriatelyset. In addition, the number of levels may be different from that of theenergy dial 811.

In this manner, in Example 1, two operations performed by a surgeonduring surgery are the increase/decrease operation of the energy E usingthe energy dial 811 and the increase/decrease operation of therepetitive frequency using the repetitive frequency dial 813. Also, therising frequency is fixed, and a table of the correspondencerelationships between the energies E and the voltage magnitudes at apredetermined rising frequency for each repetitive frequency is made inadvance. For example, in a case where the rising frequency is f5 shownin FIG. 11, the voltage magnitudes V51, V52, and the like atintersection points A51, A52, and the like, with each contour line areassociated with the energies E51, E52, and the like on the correspondingcontour lines, the rising frequency is set to f5, and a data table atthe repetitive frequency F51 is made. Data tables are made for otherrepetitive frequencies in the same manner.

Here, the voltage magnitude is fixed and a data table is made. Incomparison, a table may be made by determining a reference line in thecoordinate space shown in FIG. 11 and acquiring the rising frequency andthe voltage magnitude at each intersection point at which the referenceline intersects with each contour line of the energy E. For example, ina case where a straight line illustrated in a dotted line shown in FIG.11 is the reference line, the rising frequencies and the voltagemagnitudes at intersection points with each contour line are associatedwith the energies E51, E52, and the like on the corresponding contourline and a data table thereof may be made. Further, the reference lineillustrated in the dotted line in FIG. 11 may not be a straight line,for example, may be a curve.

Also, the respective energies E51, E52 and the like on the respectivecontour lines are allocated as the energy instructing value in ascendingorder to the dial positions 1, 2, and the like of the energy dial 811.Accordingly, the energy E can be changed by an amount of the same extentwhen the energy dial 811 moves to a position one scale apart.

Meanwhile, the respective repetitive frequencies listed on the datatable are allocated as the repetitive frequency instructing value in theorder from the lower value to the dial positions 1, 2, and the like ofthe repetitive frequency dial 813. For example, when the repetitivefrequency dial 813 moves through the scales without a movement of theenergy dial 811, it is possible to adjust a cutting speed withoutchanging the energy E.

The power button 82 is for switching between ON and OFF of the power.The ejection button 84 is for switching between the ejection start andthe ejection stop of the pulsed liquid jet and provides the samefunction as that of the ejection pedal 83 shown in FIG. 1. The pumpdrive button 85 is for switching between supply start and supply stop ofthe liquid to the liquid ejection device 30 from the feeding pump device20.

In addition, on the liquid crystal monitor 87 of the operation panel80-1, a display screen, which displays the energy E, that is,primary-jet energy [μJ] 851 for one pulse, a repetitive frequency [Hz]853, energy per unit time, which is obtained by multiplying the energyand the repetitive frequency, that is, power [mW] 855, is displayed, andcurrent values of the respective values (hereinafter, collectivelyreferred to as energy information) are renewed and displayed. Here, avalue displayed in the primary-jet energy 851 is the current value ofthe energy instructing value and a value displayed on the repetitivefrequency 853 is the repetitive frequency instructing value. A surgeoncan check the current values of the energy E, the repetitive frequency,or the energy (power) per unit time, related to the pulsed liquid jetejected from the liquid ejection opening 61, on the display screenduring surgery and can perform operations.

Further, on the display screen during surgery, three values of theenergy E, the repetitive frequency, and the energy per unit time neednot to be displayed as shown in FIG. 12 and a configuration in which atleast one of the energy E and the repetitive frequency is displayed maybe employed. In addition, one or both of the current rising frequency(or rising time Tpr) and the voltage magnitude, as well as the energy Eor the repetitive frequency, may be together displayed. In addition, thedisplay of the respective values is not limited to a case of displayingof the numerical values shown in FIG. 12, the display may be performedby a meter display or changes of the energy E, the repetitive frequency,or the like along with the increase/decrease operation from the ejectionstart of the pulsed liquid jet may be displayed as a graph.

FIG. 13 is a block diagram showing an example of a functionalconfiguration of the liquid ejection control device according toExample 1. As shown in FIG. 13, the liquid ejection control device 70-1includes an operation unit 71, a display unit 73, a controller 75, and astorage unit 77.

The operation unit 71 is realized by various switches such as a buttonswitch, a lever switch, a dial switch, a pedal switch, input devicessuch as a touch panel, a trackpad, a mouse, or the like, and anoperation signal in response to an operation input is output to thecontroller 75. The operation unit 71 includes the energy dial 811 andthe repetitive frequency dial 813. In addition, although not shown, theoperation unit 71 includes the ejection pedal 83 in FIG. 1, the powerbutton 82, the ejection button 84 and the pump drive button 85 on theoperation panel 80-1 shown in FIG. 12.

The display unit 73 is realized by a display device such as a liquidcrystal display (LCD) or an electroluminescence (EL) display and variousscreens such as the display screen shown in FIG. 12 are displayed basedon the display signal input from the controller 75. For example, theliquid crystal monitor 87 in FIG. 12 corresponds to the display unit.

The controller 75 is realized by a microprocessor such as a centralprocessing unit (CPU) or a digital signal processor (DSP), a controldevice such as an application specific integrated circuit (ASIC), and acomputing device, and controls collectively the respective units of theliquid ejection system 1. The controller 75 includes a piezoelectricelement control unit 751, a pump control unit 756, and an energy displaycontrol unit 757 as a display control unit. Further, the respectiveunits configuring the controller 75 may be configured of hardware suchas a dedicated module circuit.

The piezoelectric element control unit 751 includes a rising frequencysetting section 752, a voltage magnitude setting section 753, and arepetitive frequency setting section 754. Depending on the dial positionof the energy dial 811 and the dial position of the repetitive frequencydial 813, the rising frequency setting section 752 sets the risingfrequency of the drive voltage waveform, the voltage magnitude settingsection 753 sets the voltage magnitude of the drive voltage waveform,and the repetitive frequency setting section 754 sets the repetitivefrequency of the drive voltage waveform.

The piezoelectric element control unit 751 sets the drive voltagewaveform in response to the rising frequency, the voltage magnitude, andthe repetitive frequency set by the respective sections 752, 753, and754 and performs control of applying the drive signal of the setwaveform to the piezoelectric element 45. At this time, as a risingshape setting unit, the piezoelectric element control unit 751changeably sets a shape of a waveform (falling waveform) of a fallingportion of the drive voltage waveform in the manner shown in FIG. 10Asuch that the repetitive frequency becomes a frequency set as therepetitive frequency instructing value by the repetitive frequencysetting section 754.

The pump control unit 756 outputs a drive signal to the feeding pumpdevice 20 and drives the feeding pump device 20. The energy displaycontrol unit 757 performs control of displaying on the display unit 73an energy instructing value (that is, a current value of the energy E)allocated to a dial position of the energy dial 811 being selected, arepetitive frequency instructing value (that is, a current value of therepetitive frequency) allocated to a dial position of the repetitivefrequency dial 813 being selected, and energy per unit time, which isobtained by multiplying the above values.

The storage unit 77 is realized by various integrated circuit (IC)memories such as read only memory (ROM), flash ROM, or random accessmemory (RAM), or a recording medium such as a hard disk. In the storageunit 77, a program for causing the liquid ejection system 1 to operateand realizing various functions provided in the liquid ejection system1, data used during execution of the program, or the like is stored inadvance, or the program and the data are temporarily stored for eachprocess.

In addition, in the storage unit 77, an energy conversion table 771 isstored. The energy conversion table 771 is a data table in whichcorrespondence relationships among the energy E, the rising frequency,and the voltage magnitude for each repetitive frequency described aboveare set with reference to FIG. 11.

FIG. 14 is a diagram showing an example of a data configuration of theenergy conversion table 771. As shown in FIG. 14, the energy conversiontable 771 is a data table in which the dial position (scale) of therepetitive frequency dial 813, the repetitive frequency instructingvalue allocated to the dial position, the dial position of the energydial 811, the energy instructing value allocated to the dial position,the voltage magnitude, and the rising frequency are associated and acorrespondence relationship between the energy E and the voltagemagnitude at a predetermined rising frequency f_001 is set for eachrepetitive frequency.

With reference to the energy conversion table 771, the rising frequencysetting section 752 fixedly sets the rising frequency to be f_001. Thevoltage magnitude setting section 753 reads and sets the voltagemagnitude corresponding to combination of the respective dial positionsof the energy dial 811 and the repetitive frequency dial 813 beingselected, from the energy conversion table 771, and reads the voltagemagnitude corresponding to combination of the dial positions of therespective dials 811 and 813 from the energy conversion table 771 andthe setting is renewed in a case where one of the energy dial 811 andthe repetitive frequency dial 813 is operated.

In addition, the repetitive frequency setting section 754 reads therepetitive frequency instructing value corresponding to the dialposition of the repetitive frequency dial 813 being selected from theenergy conversion table 771 and sets the repetitive frequency and readsthe repetitive frequency instructing value of the selected dial positionfrom the energy conversion table 771 and renews the setting of therepetitive frequency in a case where the repetitive frequency dial 813is operated.

Flow of Process

FIG. 15 is a flowchart showing a flow of a process which is performed bythe controller 75 on the occasion of ejection of a pulsed liquid jet.First, the pump control unit 756 drives the feeding pump device 20, thepiezoelectric element control unit 751 drives the piezoelectric element45, and the ejection of the pulsed liquid jet is started (step S111). Atthis time, the rising frequency setting section 752 reads and sets therising frequency set in the energy conversion table 771, as a fixedvalue. In addition, the voltage magnitude setting section 753 acquiresdial positions of the energy dial 811 and the repetitive frequency dial813 being selected and reads and sets the voltage magnitudecorresponding to the combination thereof from the energy conversiontable 771. Further, the repetitive frequency setting section 754 readsthe repetitive frequency instructing value allocated to the dialposition of the repetitive frequency dial 813 being selected from theenergy conversion table 771 and sets the repetitive frequency. Also, thepiezoelectric element control unit 751 sets the drive voltage waveformdepending on the rising frequency, the voltage magnitude, and therepetitive frequency and applies the drive signal of the set drivevoltage waveform to the piezoelectric element 45.

In addition, the energy display control unit 757 performs control ofdisplaying the energy information on the display unit 73 (step S113).For example, the energy display control unit 757 reads the energyinstructing value allocated to the dial position of the energy dial 811from the energy conversion table 771 and the energy display control unitcalculates energy per unit time, which is a product of the above energyinstructing value and the repetitive frequency instructing value read instep S111. Also, the energy display control unit 757 performs a displayprocess of the display screen on which the energy instructing value, therepetitive frequency instructing value, and the energy per unit time,are displayed as energy information, on the display unit 73. Further, interms of the energy per unit time, a calculation configuration is notlimited to a configuration in which calculation is performed in displaycontrol of the energy information and a configuration in which theenergy is set in the energy conversion table 771 or the like and is readmay be employed.

Then, the controller 75 monitors an operation of the energy dial 811 instep S115 until it is determined that the ejection of the pulsed liquidjet is ended by the operation of the ejection pedal 83 and the ejectionbutton 84 (NO in step S133) and the controller monitors an operation ofthe repetitive frequency dial 813 in step S123.

Also, in a case where the energy dial 811 is operated (YES in S115), thevoltage magnitude setting section 753 reads the voltage magnitudecorresponding to the combination of the selected dial position and thedial position of the repetitive frequency dial 813 being selected fromthe energy conversion table 771 and renews the setting of the voltagemagnitude (step S117). Then, the piezoelectric element control unit 751sets the drive voltage waveform depending on the set repetitivefrequency, the rising frequency, and the voltage magnitude and appliesthe drive signal of the set drive voltage waveform to the piezoelectricelement 45 (step S119).

In addition, the energy display control unit 757 reads the energyinstructing value allocated to the selected dial position from theenergy conversion table 771 and performs control of renewal of displayon the display unit 73 (step S121).

Meanwhile, in a case where the repetitive frequency dial 813 is operated(YES in step S123), the repetitive frequency setting section 754 readsthe repetitive frequency instructing value allocated to the selecteddial position from the energy conversion table 771 and renews thesetting of the repetitive frequency (step S125). Subsequently, thevoltage magnitude setting section 753 reads the voltage magnitudecorresponding to the combination of the selected dial position and thedial position of the energy dial 811 being selected, from the energyconversion table 771, and renews the setting of the voltage magnitude(step S127). Then, the piezoelectric element control unit 751 sets thedrive voltage waveform depending on the set repetitive frequency, therising frequency, and the voltage magnitude and applies the drive signalof the set drive voltage waveform to the piezoelectric element 45 (stepS129).

In addition, the energy display control unit 757 reads the repetitivefrequency allocated to the selected dial position from the energyconversion table 771 and performs control of renewal of display on thedisplay unit 73 (step S131).

According to Example 1, a correspondence relationship between the energyE and the voltage magnitude at the predetermined rising frequency ateach repetitive frequency is set in advance. Therefore, it is possibleto set the optimal voltage magnitude for achieving the cutting depth andthe cutting volume as exact as an operational sense based on thecorrespondence relationship and to control the drive voltage waveform ofthe piezoelectric element 45. For example, when the energy dial 811moves to a position one scale apart, the energy E is changed by anamount corresponding to a scale interval. Therefore, it is possible torealize the cutting depth or the cutting volume as intended by a userand as exact as the operational sense and it is possible to improveusability.

In addition, it is possible to increase and decrease the repetitivefrequency such that the energy E becomes the energy instructing value.Accordingly, when the scale of the energy dial 811 is not changed andonly the scale of the repetitive frequency dial 813 is changed, thecutting depth or the cutting volume is maintained to be constant by thepulsed liquid jet for one pulse, it is possible to adjust the cuttingspeed as intended to be proportional to the repetitive frequency, and animprovement of the usability is achieved.

Example 2

Next, Example 2 is described. The same signs are assigned to the samecomponents as those in Example 1. FIG. 16 is a diagram showing anoperation panel 80-2 provided in a liquid ejection control device 70-2according to Example 2. As shown in FIG. 16, on the operation panel80-2, the energy dial 811, the repetitive frequency dial 813, arisingfrequency dial 815 a as a third operation unit, the power button 82, theejection button 84, the pump drive button 85, and the liquid crystalmonitor 87 are disposed.

The rising frequency dial 815 a is for inputting an instructing value ofa rising frequency (rising frequency instructing value) as a thirdinstructing value, and has a configuration in which five-level dialpositions, to which, for example, scales of “1” to “5” are assigned, areselectable. Similar to the repetitive frequency dial 813, the risingfrequency dial 815 a may also have the configuration in which anactivate switch is provided. A surgeon increases or decreases the risingfrequency in five levels by switching between the dial positions of therising frequency dial 815 a. A rising frequency instructing value isallocated to each position of the dial in advance such that the risingfrequency is increased by a constant amount in proportion to a numericalvalue on a corresponding scale. Further, the number of levels of thedial positions is not limited to five and may be appropriately set. Inaddition, the number of levels may be different from that of the energydial 811 or the repetitive frequency dial 813.

In this manner, in Example 2, three operations performed by a surgeonduring surgery are the increase/decrease operation of the energy E usingthe energy dial 811, the increase/decrease operation of the repetitivefrequency using the repetitive frequency dial 813, and theincrease/decrease operation of the rising frequency using the risingfrequency dial 815 a, and the correspondence relationship between theenergy E, the rising frequency, and the voltage magnitude for eachrepetitive frequency is listed in a table. When the energy E51 shown inFIG. 11 is focused, for example, rising frequencies f61, f62, and thelike, having the same frequency interval and voltage magnitudes V61,V62, and the like at intersection points A61, A62, and the like, witheach contour line are associated with each other and a data table ismade. Also, the rising frequencies f61, f62, and the like, are allocatedas the rising frequency instructing values in this order to therespective dial positions 1, 2, and the like of the rising frequencydial 815 a.

FIG. 17 is a block diagram showing an example of a functionalconfiguration of the liquid ejection control device according to Example2. As shown in FIG. 17, the liquid ejection control device 70-2 includesan operation unit 71 a, the display unit 73, a controller 75 a, and astorage unit 77 a.

The operation unit 71 a includes the energy dial 811, the repetitivefrequency dial 813, and the rising frequency dial 815 a.

In addition, the controller 75 a includes a piezoelectric elementcontrol unit 751 a, the pump control unit 756, and the energy displaycontrol unit 757. The piezoelectric element control unit 751 a includesa rising frequency setting section 752 a, a voltage magnitude settingsection 753 a, and the repetitive frequency setting section 754.

In the storage unit 77 a, an energy conversion table 771 a is stored.FIG. 18 is a diagram showing an example of a data configuration of theenergy conversion table 771 a in Example 2. As shown in FIG. 18, theenergy conversion table 771 a is a data table in which the dial position(scale) of the repetitive frequency dial 813, the repetitive frequencyinstructing value allocated to the dial position, the dial position ofthe energy dial 811, the energy instructing value allocated to the dialposition, and the dial position of the rising frequency dial 815 a, therising frequency instructing value allocated to the dial position, andthe voltage magnitude are associated and a correspondence relationshipamong the energy E and the voltage magnitude, and the rising frequencyis set for each repetitive frequency.

With reference to the energy conversion table 771 a, the risingfrequency setting section 752 a reads the rising frequency instructingvalue corresponding to the dial position of the rising frequency dial815 a being selected, from the energy conversion table 771 a and setsthe rising frequency, and the repetitive frequency setting section readsthe rising frequency instructing value of the selected dial positionfrom the energy conversion table 771 a and renews the setting of therising frequency in a case where the rising frequency dial 815 a isoperated. The voltage magnitude setting section 753 a reads and sets thevoltage magnitude corresponding to combination of the respective dialpositions of the energy dial 811, the repetitive frequency dial 813, andthe rising frequency dial 815 a, being selected from the energyconversion table 771 a, and reads the voltage magnitude corresponding tocombination of the dial positions of the respective dials 811,813, and815 a from the energy conversion table 771 a and the setting is renewedin a case where one of the energy dial 811, the repetitive frequencydial 813, and the rising frequency dial 815 a is operated.

Flow of Process

FIG. 19 is a flowchart showing a process which is performed by thecontroller 75 a on the occasion of ejection of a pulsed liquid jet.Further the same signs are assigned to the same processes as those inFIG. 15.

In Example 2, in step S111, the rising frequency setting section 752 areads the rising frequency instructing value allocated to the dialposition of the rising frequency dial 815 a being selected from theenergy conversion table 771 a and sets the rising frequency.

In addition, in step S233, the operation of the rising frequency dial815 a is monitored. Also, in a case where the rising frequency dial 815a is operated (YES instep S233), the rising frequency setting section752 a reads the rising frequency instructing value allocated to theselected dial position from the energy conversion table 771 a and renewsthe setting of the rising frequency (step S235). Subsequently, thevoltage magnitude setting section 753 a reads the voltage magnitudecorresponding to the combination of the selected dial position and therespective dial positions of the energy dial 811 and the risingfrequency dial 815 a being selected from the energy conversion table 771a and renews the setting of the voltage magnitude (step S237). Then, thepiezoelectric element control unit 751 a sets the drive voltage waveformdepending on the set repetitive frequency, the rising frequency, and thevoltage magnitude and applies the drive signal of the set drive voltagewaveform to the piezoelectric element 45 (step S239).

According to Example 2, a correspondence relationship between the energyE, the rising frequency, and the voltage magnitude is set for eachrepetitive frequency in advance and it is possible to control the drivevoltage waveform of the piezoelectric element 45 such that the energy Ebecomes the energy instructing value even when the rising frequency isincreased or decreased.

Further, in the embodiment described above, the case where the energy Eis increased or decreased in a stepwise manner through an operation ofthe energy dial 811, the case where the repetitive frequency isincreased or decreased in a stepwise manner through an operation of therepetitive frequency dial 813, and the case where the rising frequencyis increased or decreased in a stepwise manner through an operation ofthe rising frequency dial 815 a, are described. In comparison, therespective dials 811, 813, 815 a may have a configuration in which theenergy instructing value, the repetitive frequency instructing value, orthe rising frequency instructing value can be steplessly adjusted evenat a position (intermediate position) between the dials to which scalesare assigned.

As a specific process, for example, when the energy dial 811 is focusedand a dial position between the scales is selected, with reference tothe energy conversion table 771 (FIG. 14) or the energy conversion table771 a (FIG. 18), the energy instructing value associated with the dialposition of the scales before and after the selected energy E and thevoltage magnitudes corresponding to these energy instructing values areread. Also, linear interpolation is performed using the respective readvoltage magnitudes and a voltage magnitude corresponding to the energy Ebetween currently selected dial positions is specified.

In order to achieve higher accuracy, the voltage magnitudescorresponding to the dial positions (energy instructing values) of notonly the scales before and after, but also scales before and after onescale further of the selected energy E may be read. Also, polynomialinterpolation may be performed using the respective read voltagemagnitudes and a voltage magnitude corresponding to the energy E betweenthe currently selected dial positions may be specified.

In addition, even in a case where the position (intermediate position)between the dials of the repetitive frequency dial 813 or the risingfrequency dial 815 a is selected, it is possible to specify a voltagemagnitude by performing the same interpolation.

In addition, in the embodiment described above, as described withreference to FIG. 10A, in order to increase and decrease the repetitivefrequency, the rising shape is changeably set. In comparison, the entiredrive voltage waveform is simply widened or contracted in the time axisdirection, and thereby the repetitive frequency may be increased anddecreased. In this case, a simulation, which is performed when theenergy conversion tables 771 and 771 a are made, is performed while therepetitive frequency is changed in the manner described above.

In addition, in the embodiment described above, the rising frequency isillustrated as a rising index value. In comparison, instead of therepetitive frequency, the rising time Tpr may be used.

In addition, the energy dial 811, the repetitive frequency dial 813, andthe rising frequency dial 815 a are not limited to a case of beingrealized by a dial switch and, for example, the dials may be realized bya lever switch, a button switch, or the like. In addition, the dials maybe realized by a key switch through software, or the like, with thedisplay unit 73 as a touch panel. In this case, a user operates thetouch panel which is the display unit 73 and inputs the energyinstructing value, the repetitive frequency instructing value, and therising frequency instructing value.

In addition, in the embodiment described above, the piezoelectricelement control units 751 and 751 a are described to set the drivevoltage waveform depending on the set rising frequency, the voltagemagnitude, and the repetitive frequency (for example, step S111, S119,or the like in FIG. 15). In comparison, for each one of the possiblecombinations of the rising frequency, the voltage magnitude, and therepetitive frequency, the drive voltage waveform for one cycle may begenerated in advance and may be stored as waveform data associated withthe corresponding combination, in the storage units 77 and 77 a. Also,the waveform data corresponding to the combination of the set risingfrequency, the voltage magnitude, and the repetitive frequency may beread and a drive signal depending on the read waveform data may beapplied to the piezoelectric element 45.

In addition, in the embodiment described above, a configuration, inwhich the pulsed liquid jet having the momentum in the range from 2 nNsto 2 mNs or the kinetic energy in the range from 2 nJ to 200 mJ isejected, is disclosed and more preferably, a configuration, in which thepulsed liquid jet having the momentum in the range from 20 nNs to 200μNs or the kinetic energy in the range from 40 nJ to 10 mJ is ejected,may be employed. In this manner, it is possible to appropriately cut aliving tissue or a gel material.

What is claimed is:
 1. A liquid ejection control device in which apredetermined drive voltage waveform is applied to a piezoelectricelement to control the ejection of a pulsed liquid jet of liquid havinga pulsed shape from a liquid ejection device that uses the piezoelectricelement, the liquid ejection control device comprising: a firstoperation unit for inputting a first instructing value related tokinetic energy of the pulsed liquid jet; a second operation unit forinputting a second instructing value related to a number of times anejection of the pulsed liquid is performed per unit time; and a voltagemagnitude setting section that sets voltage magnitude of the drivevoltage waveform such that the kinetic energy becomes the firstinstructing value, based on an index value related to rising of thedrive voltage waveform and the second instructing value.
 2. The liquidejection control device according to claim 1, further comprising: athird operation unit for inputting a third instructing value related tothe index value.
 3. The liquid ejection control device according toclaim 1, further comprising: a falling shape setting section thatchangeably sets a falling shape of the drive voltage waveform dependingon the second instructing value.
 4. The liquid ejection control deviceaccording to claim 1, further comprising: a display control unit thatperforms control of display of at least one of the first instructingvalue and the second instructing value.
 5. The liquid ejection controldevice according to claim 1, wherein the liquid ejection device iscontrolled such that the pulsed liquid jet has momentum in a range from2 nNs (nanonewton seconds) to 2 mNs (millinewton seconds) or kineticenergy in a range from 2 nJ (nanojules) to 200 mJ (millijules).
 6. Theliquid ejection control device according to claim 1, wherein the liquidejection device is controlled to cut a living tissue using the pulsedliquid jet.
 7. A liquid ejection system comprising: the liquid ejectioncontrol device according to claim 1; a liquid ejection device; and afeeding pump device.
 8. A liquid ejection system comprising: the liquidejection control device according to claim 2; a liquid ejection device;and a feeding pump device.
 9. A liquid ejection system comprising: theliquid ejection control device according to claim 3; a liquid ejectiondevice; and a feeding pump device.
 10. A liquid ejection systemcomprising: the liquid ejection control device according to claim 4; aliquid ejection device; and a feeding pump device.
 11. A liquid ejectionsystem comprising: the liquid ejection control device according to claim5; a liquid ejection device; and a feeding pump device.
 12. A liquidejection system comprising: the liquid ejection control device accordingto claim 6; a liquid ejection device; and a feeding pump device.
 13. Acontrol method in which a predetermined drive voltage waveform isapplied to a piezoelectric element to control the ejection of a pulsedliquid jet of liquid having a pulsed shape from a liquid ejection devicethat uses the piezoelectric element, the control method comprising:inputting a first instructing value related to kinetic energy of thepulsed liquid jet; inputting a second instructing value related to thenumber of times an ejection of the pulsed liquid is performed per unittime; and setting voltage magnitude of the drive voltage waveform suchthat the kinetic energy becomes the first instructing value, based on arising index value related to rising of the drive voltage waveform andthe second instructing value.